Constriction of natural body lumens, such as those of the human gastrointestinal tract, can occur in numerous ways. Some strictures are caused by muscular spasm, others by disease, and others by injury. Regardless of the cause, the typical method of treatment is to physically dilate the region using a medical device designed for that purpose.
Several types of devices are used for dilation. One generally established type is a bougie. Bougie tubes may be in the form of a mercury- or tungsten-filled tube with a tapered end that gradually opens the strictured esophagus as it is pushed past the treatment site. These devices come in a series of increasing sizes, each tube having a single effective dilating diameter, generally between 10 and 60 French. (French is a measure of circumference based on the diameter in millimeters, mm.) The bougie is typically introduced blindly after the physician has judged the proper beginning size with an endoscope. Some physicians follow a rule of thumb not to dilate a stricture more than three successive French sizes (3 mm) in a single session. If the lumen has not satisfactorily been opened after three sizes, the patient returns at a later time for another treatment session.
Another type of device is a wire-guided dilator. These devices are passed into the patient over a guidewire that has been pre-fed along a lumen of the gastrointestinal tract. The guidewire keeps the tip of the device in the lumen while it is being passed, to avoid perforating through the wall of the lumen. These devices have a single outer dilating diameter and typically have a radiopaque component so that they are visible under fluoroscopy. The following patent documents disclose various devices in the art: U.S. Pat. No. 5,366,471; U.S. Pat. No. 6,334,863; U.S. Pat. No. 5,766,202; and GB 2023009A.
A third type of dilating device is a balloon. Balloon dilators may be comprised of polyethylene, and may be introduced through the working channel of an endoscope. The physician views the proximal end of a stricture site with an endoscope and introduces the deflated balloon into the narrowed area. The balloon is then inflated with saline or other fluid to effectively open the stricture site pneumatically. Balloons provide the advantages of multiple dilator diameters with a single intubation, passage through the working channel of an endoscope, and visualization of a stricture site from the proximal end.
Other devices such as double tapered bougies, pneumatic bougies, illuminating bougies, solid dilator devices attached to the distal end of an endoscope, and variable stiffness dilators have been previously described in the art. The following patent documents disclose various types of devices in the art: U.S. Pat. No. 6,010,520; U.S. Pat. No. 4,832,691; U.S. Pat. No. 5,624,432; U.S. Pat. No. 5,718,666; WO 98/47422.